The present invention relates to bearings of the type adapted to rotatively support a load for rotation about the bearing axis and in particular to an improved bearing assembly made in accordance with a novel method disclosed herein and claimed in co-pending application of the same inventors filed concurrently herewith and entitled "Method of Making a Ball Bearing Assembly" now U.S. Pat. No. 3,858,288.
Two prior art patents which disclose methods of making a bearing assembly are U.S. Pat. No. 822,723 and U.S. Pat. No. 2,702,216. In the former patent the bearing balls are assembled into the bearing with the inner race member eccentrically oriented relative to the outer race member. After the bearing balls have been so assembled the inner race member is made concentric with the outer race member while the balls are distributed circumferentially around and between the two members and riding in the raceways thereof. The bearing balls are customarily caged. One problem with this arrangement is that a full complement of bearing balls cannot be assembled into the bearing. In the latter patent the outer race member is split by what is termed either a crack line or a split line. A full complement of bearing balls is assembled into the bearing by first separating the ends of the outer race member at the split line to thereby temporarily circumferentially expand the outer race member. The balls are then assembled into the bearing after which the outer race member is released. The outer race member returns it to its initial shape, thereby constraining the bearings between the raceways of the inner and outer race members. The method of the latter patent provides an axial groove in the outer surface of outer race member which facilitates the formation of the split line. Thus, in the finished bearing assembly according to U.S. Pat. No. 2,702,216, an axial groove exists in the outer surface of the outer race member.
It is also known to provide a radial passage in the outer race member through which lubricant can be introduced into the bearing assembly. As will be seen in the within-detailed description, the present invention provides a bearing having a split line through the outer race member which intercepts a radial passage extending through the member. The radial passage facilitates creation of the split line in the initially circumferentially continuous outer race member.
Heretofore, bearings of the type to which the present invention relates have proved unsatisfactory when used in applications where relatively high-impact loads are repeatedly encountered. This is the case for the wheel bearings used in guiding the lift of a fork lift truck where presently used bearings are only marginal in performance. One solution to the problem, of course, is to replace the bearings of the type shown in U.S. Pat. No. 822,723 with others of the same type, but larger, having a higher load rating. However, such a solution is undesirable since it means that due to the increase in bearing size, the entire bearing assembly, including related portions of the lift construction will be larger and result in increased cost. On the other hand, it has been found that bearings of the type shown in U.S. Pat. No. 2,702,216 have chips, spalls and other surface imperfections formed at the raceway along the crack line as a result of the methods described therein for causing the crack.
Among the objects of the present invention are to provide an improved, high-impact capacity bearing which: lasts longer than prior bearings used for high-impact applications, yet is of comparable size and weight; is easier to manufacture and assemble; can be manufactured economically; contains a full complement of bearing elements; and in other respects achieves important advantages over prior bearings.
When utilized in connection with the lift of a fork lift truck the present invention also provides an improved bearing and wheel construction which: is more durable, more shock-resistant, and can last longer than prior constructions.
The foregoing objects, as well as additional objects, advantages and benefits of the invention will be seen in the ensuing description and claims which are to be taken in conjunction with the accompanying drawings .